It is generally known for a silver-containing catalyst to be employed in the preparation of ethylene oxide. See for example U.S. Pat. No. 3,962,136 and also the literature cited therein. In order to obtain improved silver catalysts, efforts have been directed for many years towards modifying the silver catalysts with the aid of promoters. For example, the above-mentioned U.S. Pat. No. 3,962,136 describes a process in which a silver compound is applied to a carrier, after which the applied silver compound is reduced to silver and in which additionally a promoter in the form of potassium oxide, rubidium oxide or cesium oxide or a mixture thereof is present on the carrier.
In co-pending U.S. patent application Ser. No. 874,924, filed June 16, 1986, now U.S. Pat. No. 4,701,437, is described a process for the preparation of a silver-containing catalyst suitable for the oxidation of ethylene to ethylene oxide, whereby a silver compound and, if desired, a promoter are applied to a carrier, after which the silver compound is reduced to metallic silver, and in which process the carrier has been prepared by mixing an aluminum compound with a tin compound and by calcining the obtained mixture. The catalyst has a high activity.
There has now been found that a silver catalyst may be prepared with a high activity, a high selectivity and a very high stability by the process of the instant invention.